From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 49BC8AD35; Mon, 3 Jun 2024 02:46:42 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717382803; cv=none; b=q9kKsSWFoQNbW26VB/svcpzfnMFenuL4r7nPM8z+TWvi1aL3ml1U3O3qzhJ3dnWWFnwzLLwmn7MD5oH43d/EuXD3W7UKZkFUa1pnRfTwDcsPrp1qsFnkrnA8qG3qqxjaZTqDMKG1tl5C3bW1cUdWD+IIk8wTPA1xkmKaX+hiklc= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1717382803; c=relaxed/simple; bh=hUy2QzJqjW+BmS42fRWN5RITmP+ikPzZbR/VgKNapZ4=; h=Date:From:To:Cc:Subject:Message-Id:In-Reply-To:References: Mime-Version:Content-Type; b=nDUMhMctd4JSCfPU2VnAJUJ24Vl/CJRsDHsfC0NGCMGbF+vhdoKCiPZymNx8tKY/QuOIbMAXDqJ6M5Sdwg1nqnIiocdXyHxz9U0hHqLOry4PefM5pU/jbq+U3eCya8tlz6OsFczaWnowPdwYrVjUT1IErusecu85EbqSNnCHqgQ= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=YyzFy5ZX; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="YyzFy5ZX" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 944DAC2BBFC; Mon, 3 Jun 2024 02:46:38 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1717382802; bh=hUy2QzJqjW+BmS42fRWN5RITmP+ikPzZbR/VgKNapZ4=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=YyzFy5ZXAdsf4yQwWKi/nxyorWVS+sxftkUFmJAA9Nkbq2yEkrazh8xULU7LqpH/o NDv24cefagH8eTH2swd0ak/N4rQCDmL2d5nRONe1F+0cIvdV2BEOVYq4nwOZ8Pgh8T Whqa49Pt6R5q7Eqa8dlpIru1eQdjYzHzT20v5ejHVH8Y9IeWTCELpO22NAoiTsVohh gY9dyLlPy4duRUiBRehICnIn7EKIaYyVGVV/Vtvje/+IxKARVjKGz5Z3YrsF4Mfybp KyahpqeSCcZi4bWpVkU9zMLap7s/IqQ2DtXUg+USMmpStzNxc9IrQv5Te9y3sj+Sum 20VD+amXMkCgw== Date: Mon, 3 Jun 2024 11:46:36 +0900 From: Masami Hiramatsu (Google) To: Steven Rostedt Cc: linux-kernel@vger.kernel.org, linux-trace-kernel@vger.kernel.org, Mark Rutland , Mathieu Desnoyers , Andrew Morton , Alexei Starovoitov , Florent Revest , Martin KaFai Lau , bpf , Sven Schnelle , Alexei Starovoitov , Jiri Olsa , Arnaldo Carvalho de Melo , Daniel Borkmann , Alan Maguire , Peter Zijlstra , Thomas Gleixner , Guo Ren Subject: Re: [PATCH v2 10/27] ftrace: Add subops logic to allow one ops to manage many Message-Id: <20240603114636.63b5abe2189cb732bec2474c@kernel.org> In-Reply-To: <20240602220613.3f9eac04@gandalf.local.home> References: <20240602033744.563858532@goodmis.org> <20240602033832.709653366@goodmis.org> <20240603103316.3af9dea3214a5d2bde721cd8@kernel.org> <20240602220613.3f9eac04@gandalf.local.home> X-Mailer: Sylpheed 3.7.0 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Precedence: bulk X-Mailing-List: linux-trace-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit On Sun, 2 Jun 2024 22:06:13 -0400 Steven Rostedt wrote: > > > +/* Make @ops trace evenything except what all its subops do not trace */ > > > +static struct ftrace_hash *intersect_hashes(struct ftrace_ops *ops) > > > +{ > > > + struct ftrace_hash *new_hash = NULL; > > > + struct ftrace_ops *subops; > > > + int size_bits; > > > + int ret; > > > + > > > + list_for_each_entry(subops, &ops->subop_list, list) { > > > + struct ftrace_hash *next_hash; > > > + > > > + if (!new_hash) { > > > + size_bits = subops->func_hash->notrace_hash->size_bits; > > > + new_hash = alloc_and_copy_ftrace_hash(size_bits, ops->func_hash->notrace_hash); > > > + if (!new_hash) > > > + return NULL; > > > > If the first subops has EMPTY_HASH, this allocates small empty hash (!= EMPTY_HASH) > > on `new_hash`. > > Could we just change the above to be: ? > > new_hash = ftrace_hash_empty(ops->func_hash->notrace_hash) ? EMPTY_HASH : > alloc_and_copy_ftrace_hash(size_bits, ops->func_hash->notrace_hash); > if (!new_hash) > return NULL; Yeah, and if new_hash is EMPTY_HASH, we don't need looping on the rest of the hashes, right? > > > > > > > + continue; > > > + } > > > + size_bits = new_hash->size_bits; > > > + next_hash = new_hash; > > > > And it is assigned to `next_hash`. > > > > > + new_hash = alloc_ftrace_hash(size_bits); > > > + ret = intersect_hash(&new_hash, next_hash, subops->func_hash->notrace_hash); > > > > Since the `next_hash` != EMPTY_HASH but it is empty, this keeps `new_hash` > > empty but allocated. > > > > > + free_ftrace_hash(next_hash); > > > + if (ret < 0) { > > > + free_ftrace_hash(new_hash); > > > + return NULL; > > > + } > > > + /* Nothing more to do if new_hash is empty */ > > > + if (new_hash == EMPTY_HASH) > > > > Since `new_hash` is empty but != EMPTY_HASH, this does not pass. Keep looping on. > > > > > + break; > > > + } > > > + return new_hash; > > > > And this will return empty but not EMPTY_HASH hash. > > > > > > So, we need; > > > > #define FTRACE_EMPTY_HASH_OR_NULL(hash) (!(hash) || (hash) == EMPTY_HASH) > > > > if (FTRACE_EMPTY_HASH_OR_NULL(subops->func_hash->notrace_hash)) { > > free_ftrace_hash(new_hash); > > new_hash = EMPTY_HASH; > > break; > > } > > > > at the beginning of the loop. > > Also, at the end of the loop, > > > > if (ftrace_hash_empty(new_hash)) { > > free_ftrace_hash(new_hash); > > new_hash = EMPTY_HASH; > > break; > > } And we still need this (I think this should be done in intersect_hash(), we just need to count the number of entries.) > > > > > +} > > > + > > > +/* Returns 0 on equal or non-zero on non-equal */ > > > +static int compare_ops(struct ftrace_hash *A, struct ftrace_hash *B) > > > > nit: Isn't it better to be `bool hash_equal()` and return true if A == B ? > > Sure. I guess I was thinking too much of strcmp() logic :-p Yeah, it's the curse of the C programmer :( (even it is good for sorting.) Thank you, > > > > > Thank you, > > Thanks for the review. > > -- Steve > > > > > > +{ > > > + struct ftrace_func_entry *entry; > > > + int size; > > > + int i; > > > + > > > + if (!A || A == EMPTY_HASH) > > > + return !(!B || B == EMPTY_HASH); > > > + > > > + if (!B || B == EMPTY_HASH) > > > + return !(!A || A == EMPTY_HASH); > > > + > > > + if (A->count != B->count) > > > + return 1; > > > + > > > + size = 1 << A->size_bits; > > > + for (i = 0; i < size; i++) { > > > + hlist_for_each_entry(entry, &A->buckets[i], hlist) { > > > + if (!__ftrace_lookup_ip(B, entry->ip)) > > > + return 1; > > > + } > > > + } > > > + > > > + return 0; > > > +} > > > + > > > > > -- Masami Hiramatsu (Google)